Minneapolis & St. Paul ADU Rules, Setbacks, and Permits

Both Minneapolis and St. Paul allow accessory dwelling units (ADUs) on the large majority of residential lots. The rules are more permissive than most homeowners assume, and the two cities differ in ways that change what you can build.

Minneapolis

Rule	Requirement
Allowed on	Most lots with a single- or two-family dwelling
Types	Interior (basement/attic), attached addition, detached backyard unit
Max size — detached	Generally the lesser of 1,000 sq ft or 16% of lot area
Max height — detached	Typically 1.5–2 stories depending on district
Rear setback	Commonly 5 ft (alley lots often less)
Side setback	Commonly 5 ft
Parking	No additional parking required
Owner occupancy	Not required
Short-term rental	Restricted — check current STR licensing

St. Paul

Rule	Requirement
Allowed on	Most residential lots citywide
Types	Interior, attached, detached
Max size — detached	Generally up to 800–1,000 sq ft depending on lot
Rear setback	Commonly 5 ft
Side setback	Matches the principal structure requirement
Parking	No additional parking required in most districts
Owner occupancy	Not required

Both cities have moved away from owner-occupancy mandates, which is what made ADUs financeable as rentals rather than only as family housing.

The permit sequence

1. Zoning verification — confirm lot size, setbacks, and lot coverage before design. $100–$300.
2. Survey — a current certificate of survey is usually required for detached units. $600–$1,500.
3. Architectural plans and structural — $4,000–$12,000 depending on complexity.
4. Building permit — Twin Cities permit and plan review commonly runs $3,000–$8,000 on a detached ADU.
5. Sewer availability charge (SAC) — the Met Council SAC charge for a new dwelling unit is a real line item, frequently $2,500–$5,000. Budget for it; it surprises people.
6. Utility connections — separate water/sewer laterals and a new electrical service run $8,000–$25,000 depending on trench length and street cut requirements.
7. Inspections — footing, framing, rough-in, insulation, final.

Realistic timeline

• Design and engineering: 6–10 weeks
• Permit review: 4–12 weeks
• Construction: 4–7 months for detached

Total: 10–18 months from first call to certificate of occupancy. Start the zoning verification in winter so you break ground in spring.

What kills ADU projects here

• Lot coverage. Small city lots with a big house and a garage are often already at maximum impervious coverage. The garage frequently has to come down.
• Trench distance to the main. Every extra 30 feet of utility trench is real money.
• Frost footings. Minnesota requires 42-inch frost depth footings. There is no slab-on-grade shortcut for a year-round unit.
• Alley access. Great for construction staging; sometimes constrains the buildable footprint.

The financial read

A detached Twin Cities ADU runs $180,000–$320,000 all-in. It rents for $1,500–$2,400/month. That is a 12–18 year simple payback — slow as a pure investment, strong as a housing solution for family, and it adds meaningful appraised value on a lot that supports it.

An interior ADU — a basement or attic unit inside the existing envelope — runs $70,000–$140,000 and rents for nearly the same. That is the version that actually pencils.